SCHEDULE I-PARENT COMPANY FINANCIAL INFORMATION (Additional Information) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Cash dividends received from subsidiary	$ 2,300	$ 1,400	$ 800
Aggregate statutory capital and surplus in our state regulated insurance subsidiaries	7,600	8,000
Aggregate minimum regulatory requirements of statutory capital and surplus	5,200	4,800
Dividends that may be paid to the parent company without prior approval by state regulatory authorities in 2014	1,000
Dividends that were paid to the parent company without prior approval by state regulatory authorities	$ 2,300	1,400	800
Majority-Owned Subsidiary, Unconsolidated
Condensed Financial Statements, Captions [Line Items]
Interest expense on subsidiary notes payable		$ 1	$ 1